A non-volatile memory is capable of retaining data stored therein even when the power is off. Particularly, a Multiple-Times-Programmable (MTP) non-volatile memory is popular for use in modern digital products.
A MTP non-volatile memory is basically implemented with a floating gate and a control gate, wherein the written-in data is stored in the floating gate in a form of charges. A variety of manufacturing processes have been used for forming a MTP non-volatile memory, which result in different memory structures accordingly. For example, so-called triple-layer poly process, dual-layer poly process and single-layer poly process are commonly used. Please be noted that the term “poly” used herein and hereinafter is commonly used in this field for indicating the material “polysilicon”. The single-layer poly process involves less procedures compared to other processes, but the retention capability of the resulting single poly structure for retaining the charges in the floating gate is unsatisfactory. For example, when the resulting structure is subjected to baking at 250° C., charges in the floating gate are largely lost and the current intensity between the source/drain electrodes is largely decreased to a level which might result in data error.